Abstract: A gear transmission mechanism is provided between a crankshaft and the balancer shaft. The balancer shaft includes a pair of bearing portions supported for rotation on a crankcase and a gear wheel supporting portion formed in a tapering shape such that a diameter thereof decreases away from one bearing portion. A tubular boss portion is provided integrally on the driven gear wheel and has a tapering attachment hole in which the gear wheel supporting portion is fitted. A fitting recessed portion in which a pin which has an axial line along a radial direction of the balancer shaft and is fitted at a half portion on one end side thereof in a large diameter end portion of the gear wheel supporting portion is fitted at a half portion on the other end side thereof is provided on the boss portion on the large diameter end side of the attachment hole.

Abstract: A gear transmission mechanism is provided between a crankshaft and the balancer shaft. The balancer shaft includes a pair of bearing portions supported for rotation on a crankcase and a gear wheel supporting portion formed in a tapering shape such that a diameter thereof decreases away from one bearing portion. A tubular boss portion is provided integrally on the driven gear wheel and has a tapering attachment hole in which the gear wheel supporting portion is fitted. A fitting recessed portion in which a pin which has an axial line along a radial direction of the balancer shaft and is fitted at a half portion on one end side thereof in a large diameter end portion of the gear wheel supporting portion is fitted at a half portion on the other end side thereof is provided on the boss portion on the large diameter end side of the attachment hole.

Abstract: In the inlet passage structure of the V-type internal combustion engine, front and rear banks have inlet ports with a nearly identical inlet passage length, and an inlet chamber is connected to a top end openings of the inlet ports. A throttle body and the inlet chamber are offset on a side leading to a cylinder on a side away from the throttle body. The inside of the inlet chamber is formed with a nearly straight inlet passage from the throttle body to the top end opening of the inlet port leading to the cylinder bore on the side away from the throttle body, and a curved inlet passage to the top end opening of the inlet port leading to the cylinder on a close side.

Abstract: In a rotation angle sensor attaching structure for detecting rotation of a rotational angle detection object shaft through a reduction gear, an outer race of a bearing is force fitted in and secured to a central portion of the reduction gear, and an inner race of the bearing is secured to a supporting wall by a supporting bolt. A sensor-connecting element of a rotation angle sensor, which extends across a head portion of the supporting bolt, is secured integrally to an outer side face of the reduction gear. Such arrangement achieves a minimal size of the rotation angle sensor attaching structure.

Abstract: A valve train for an internal combustion engine includes a camshaft, a valve-operating cam for operating an engine valve, and a link mechanism for swinging the valve-operating cam. The valve train also includes a holder member operable to turn around the camshaft, and a drive mechanism operable to turn the holder member for varying positions of the link mechanism. The drive mechanism includes a ball screw provided perpendicularly to the camshaft, a slider threadably engaged with the ball screw, an arm member swingably attached to the slider, and a connecting bolt having one end secured to an arm-connecting portion of the arm member, and the other end secured to the holder member. In such movable valve train for an internal combustion engine, the holder member and the drive mechanism are connected to each other with a small and lightweight configuration, requiring a minimal number of parts.

Abstract: A V-type internal combustion engine having a variable valve train for keeping the height of the internal combustion engine low. Disclosed is a V-type internal combustion engine with a variable valve train that uses an actuator to vary the phase/lift amount of camshafts. The actuator is mounted on head covers for each of a plurality of cylinder blocks arranged in a V-shape. The actuator is attached to a lateral surface positioned opposite the offset direction of the head covers. In an embodiment, the actuator is attached to a lateral surface of the head covers and positioned close to the inside of the V banks.

Abstract: A valve gear for an internal combustion engine having a sub-rocker arm return spring that is shortened in a longitudinal length of a cylinder. The valve gear for the internal combustion engine is provided with a camshaft, an intake cam turning integrally with the camshaft, a valve cam for opening and closing an engine valve, a link mechanism for transmitting a valve driving force to the valve cam, a holder for supporting a sub-rocker arm support and a driving mechanism for varying a fulcrum position of the link mechanism. A valve operating characteristic can be varied with an oscillating position of the sub-rocker arm support. A sub-rocker arm is provided with a roller, an eccentrically disposed step and a link section. The step is provided with a spring socket, and a return spring is arranged intervening between the spring socket and the holder.

Abstract: A valve motion for an internal combustion engine which suppresses the height of the internal combustion engine low. In a valve motion for an internal combustion engine, a driving mechanism includes a ball screw disposed over an intake side camshaft and an exhaust side camshaft and having threaded portions provided thereon which are threaded in different directions from each other on the intake side and the exhaust side. Sliders are individually provided on the intake side and exhaust side and movable on the ball screw with connecting link members provided between the sliders and a holder member.

Abstract: A valve train for an internal combustion engine includes a camshaft, a valve-operating cam for operating an engine valve, and a link mechanism for swinging the valve-operating cam. The valve train also includes a holder member operable to turn around the camshaft, and a drive mechanism operable to turn the holder member for varying positions of the link mechanism. The drive mechanism includes a ball screw provided perpendicularly to the camshaft, a slider threadably engaged with the ball screw, an arm member swingably attached to the slider, and a connecting bolt having one end secured to an arm-connecting portion of the arm member, and the other end secured to the holder member. In such movable valve train for an internal combustion engine, the holder member and the drive mechanism are connected to each other with a small and lightweight configuration, requiring a minimal number of parts.

Abstract: In a rotation angle sensor attaching structure for detecting rotation of a rotational angle detection object shaft through a reduction gear, an outer race of a bearing is force fitted in and secured to a central portion of the reduction gear, and an inner race of the bearing is secured to a supporting wall by a supporting bolt. A sensor-connecting element of a rotation angle sensor, which extends across a head portion of the supporting bolt, is secured integrally to an outer side face of the reduction gear. Such arrangement achieves a minimal size of the rotation angle sensor attaching structure.

Abstract: In the inlet passage structure of the V-type internal combustion engine, front and rear banks have inlet ports with a nearly identical inlet passage length, and an inlet chamber is connected to a top end openings of the inlet ports. A throttle body and the inlet chamber are offset on a side leading to a cylinder on a side away from the throttle body. The inside of the inlet chamber is formed with a nearly straight inlet passage from the throttle body to the top end opening of the inlet port leading to the cylinder bore on the side away from the throttle body, and a curved inlet passage to the top end opening of the inlet port leading to the cylinder on a close side.

Abstract: A motorcycle mounted with a V-shaped engine in which a front bank and a rear bank are disposed like a V-shape and a fuel pump for fuel injection is mounted. The fuel pump is driven by a camshaft of a cylinder head, and mounted on the upside of the cylinder head. The fuel pump is fitted is the cylinder head of the front bank at the back of a head pipe. A fuel chamber is provided between the fuel pump an the injectors, the fuel chamber is disposed lengthways in the vertical direction in the V-bank space K, and a lower end part is disposed facing the sides of the injectors, and connection to the injectors by fuel pipes extending from the lower end part substantially horizontally. With this configuration, the fuel pump does not obstruct other components in the motorcycle, and is protected without a special cover.

Abstract: A valve gear for an internal combustion engine having a sub-rocker arm return spring that is shortened in a longitudinal length of a cylinder. The valve gear for the internal combustion engine is provided with a camshaft, an intake cam turning integrally with the camshaft, a valve cam for opening and closing an engine valve, a link mechanism for transmitting a valve driving force to the valve cam, a holder for supporting a sub-rocker arm support and a driving mechanism for varying a fulcrum position of the link mechanism. A valve operating characteristic can be varied with an oscillating position of the sub-rocker arm support. A sub-rocker arm is provided with a roller, an eccentrically disposed step and a link section. The step is provided with a spring socket, and a return spring is arranged intervening between the spring socket and the holder.

Abstract: A valve motion for an internal combustion engine which suppresses the height of the internal combustion engine low. In a valve motion for an internal combustion engine, a driving mechanism includes a ball screw disposed over an intake side camshaft and an exhaust side camshaft and having threaded portions provided thereon which are threaded in different directions from each other on the intake side and the exhaust side. Sliders are individually provided on the intake side and exhaust side and movable on the ball screw with connecting link members provided between the sliders and a holder member.

Abstract: A V-type internal combustion engine having a variable valve train for keeping the height of the internal combustion engine low. Disclosed is a V-type internal combustion engine with a variable valve train that uses an actuator to vary the phase/lift amount of camshafts. The actuator is mounted on head covers for each of a plurality of cylinder blocks arranged in a V-shape. The actuator is attached to a lateral surface positioned opposite the offset direction of the head covers. In an embodiment, the actuator is attached to a lateral surface of the head covers and positioned close to the inside of the V banks.